Generally, a semiconductor device, such as memory, includes contact holes or via holes to electrically connect active elements, which are formed in the lower portion thereof, to wiring layers, which are formed in the upper portion thereof. The contact holes are formed by etching an insulating layer, such as an oxide layer, from the surface thereof to a lower substrate using Reactive Ion Etching (RIE). In order to optimize etching conditions, it is required that the internal and external structure of each contact hole and the state of the underside of each contact hole be detected.
A tester for inspecting via holes or contact holes is disclosed in Korean Pat. No. 10-0388690. However, this technology was proposed to solve a problem in which, when inspection for via holes is conducted using existing Scanning Electron Microscope (SEM) equipment, the openings of the respective via holes can be detected but information about the bottom sides of the respective via holes cannot be known.
FIG. 1 shows an embodiment of Korean Pat. No. 10-0388690. In the patent specification, FIG. 1 is a diagram showing a tester for inspecting the holes of a semiconductor device. The semiconductor device tester includes an electron gun 1 for generating an electron beam 2, a condenser lens 3, an aperture plate 4 for collimating the electron beam 2, a moveable stage 6 used to radiate the electron beam 2 on the desired portions of a sample 5 by moving the sample 5, an electrode 7, a current system 9 for measuring current, which is generated by the sample 5 due to the radiation of the electron beam 2, a moved distance measurement device 8 for measuring the distance that the movable stage 6 moves, a data processor 10, such as a computer, for processing data acquired from the current system 9, and a beam control unit 11 for performing control, such as varying the acceleration voltage of the electron beam and/or varying the radiation period. The electron beam 2 radiated from the electron gun 1 is converted to a collimated beam by the condenser lens 3 and is directed toward the aperture plate 4, which has a very small aperture. The aperture plate 4 is made of a material, such as metal, and is grounded such that the radiated electrons do not accumulate in the aperture plate 4. The electron beam, having passed through the small aperture of the aperture plate 4, is a very thin beam having a cross sectional area substantially identical to the area of the aperture, and is directed toward the sample 5. This aperture plate 4 may be cooled to prevent the diameter of the aperture from being changed by thermal expansion of the aperture plate 4.
However, the conventional hole inspection apparatus, described above, is problematic in that a lot of time is taken because an electron gun 2 that generates a single electron beam is used. That is, in the case where a large number of holes must be inspected, although the respective holes are precisely inspected, a lot of time is taken, because the holes must be individually inspected. Accordingly, a lot of time is required for the manufacturing inspection of a semiconductor device, the inspection of throughholes or the like, and thus a more rapid and convenient inspection apparatus and method are required.